Drop on demand ink jet technology is widely used in the printing industry. Printers using drop on demand ink jet technology can use either thermal ink jet technology or piezoelectric technology. Even though they are more expensive to manufacture than thermal ink jets, piezoelectric ink jets are generally favored, for example because they can use a wider variety of inks.
Piezoelectric ink jet printheads include an array of piezoelectric elements (i.e., transducers or PZTs). One process to form the array can include detachably bonding a blanket piezoelectric layer to a transfer carrier with an adhesive, and dicing the blanket piezoelectric layer to form a plurality of individual piezoelectric elements. A plurality of dicing saw passes can be used to remove all the piezoelectric material between adjacent piezoelectric elements to provide the correct spacing between each piezoelectric element.
Piezoelectric ink jet printheads can typically further include a flexible diaphragm to which the array of piezoelectric elements is attached. When a voltage is applied to a piezoelectric element, typically through electrical connection with an electrode electrically coupled to a power source, the piezoelectric element bends or deflects, causing the diaphragm to flex which expels a quantity of ink from a chamber through a nozzle. The flexing further draws ink into the chamber from a main ink reservoir through an opening to replace the expelled ink.
A printhead can include several layers that form ink channels and other printhead structures. Liquid adhesive such as epoxy can be used to bond two layers together. There are typically two ways of applying liquid adhesives, direct application and through the use of B-stage materials.
Direct application can include such methods as spin-coating, screen printing, and contact printing. Spin-coating can apply a uniform layer of liquid adhesive on top surface, but cannot avoid unwanted area, such as holes. Screen printing is versatile, but may not available for liquid adhesives at low viscosity. Micro-contact printing is appropriate for a very thin layer (a few nanometers or less), targeted at molecular level applications.
B-stage materials are liquid adhesives that have been partially cured to form adhesive films. Developing liquid adhesives into B-stage films can require extensive, time-consuming research efforts.
Additional adhesive methods and structures which can overcome the deficiencies of prior adhesion methods and which can be applied to manufacturing technologies such as printhead manufacture would be desirable.